Radial entrapment neuropathy due to chronic injection-induced triceps fibrosis.

We report two patients who developed progressive, severe, painless radial neuropathies (bilateral in one, unilateral in the other) as a delayed complication of chronic intramuscular analgesic injection. In each instance, exploration of the radial nerve revealed multifocal entrapment within a densely fibrotic triceps muscle at sites between the spiral groove and distal course of the radial nerve near the elbow. Release of the nerve from constriction within the fibrotic triceps muscle produced improvement in all three affected nerves.